Mar. 4. 1918 Winter Egg Production of Rhode Island Reds 569 



DrFFERENCE IN JANUARY AND FEBRUARY EGG PRODUCTION, TAKING THE LENGTH OP 

 PAUSE INTO CONSIDERATION 



The results of an examination of this point are shown in Table XI, 

 which gives no evidence that a difference in the egg production of an 

 individual for the two months is more likely to occur in one month than 

 the other, since the number of individuals falling in the different cate- 

 gories is approximately equal, although fluctuating somewhat from year 

 to year. 



These data, taken in connection with those previously discussed 

 regarding differences in monthly production and with the observations 

 on rate of production, show that a lower rate of production for Feb- 

 ruary over January in the individual case is without significance, unless 

 associated with a definite pause. This information is of particular value 

 for those instances in which the production for February is only a few 

 eggs less than for January and which, from Pearl's data, might be con- 

 sidered to exhibit a winter cycle. 



Table XII. — Mean production of two groups of pullets hatched in April, igi6,for the 

 periods after the first egg designated in the headings 



BIRDS BEGINNING TO LAY OCT. S-DEC. 13, INCLUSIVE (80 TO 72 INDIVIDUALS^) 



Days of production . . . 



33-63 



63-93 



Mean 

 March 

 produc- 

 tion. 



Mean number of eggs 

 per period 



Mean date of begin- 

 ning and end of 

 each period 



16. 96 



Nov. 9 



to 

 Dec. 10. 



Dec. II 



to 

 Jan. 10. 



14.56 



Jan. II 



to 

 Feb. 10. 



Nov. 9 



to 

 Nov. 19. 



17-63 



Nov. 3o 



to 

 Dec. 3o. 



15-87 



Dec. 31 



to 

 Jan. 30. 



Jan. 31 



to 

 Feb. 30. 



BIRDS BEGINNING TO LAY DEC. 14-JAN. 25, INCLUSIVE (69 TO 55 INDIVIDUALS «) 



Mean number of eggs 

 per period 



Mean date of begin- 

 ning and end of 

 each period 



Jan. 3 



to 

 Feb. I. 



Feb. 3 



to 

 Mar. 3. 



Mar. 4 



to 

 Apr. 4- 



Jan. 2 



to 

 Jan. 12. 



Jan. 13 



to 

 Feb. 12. 



19-38 



Feb. 13 

 to 



Mar. 16. 



Mar. 17 



to 

 Apr. 16. 



o The variation number of individuals is due to broodiness. 



EGG PRODUCTION IN PERIODS OF DEFINITE LENGTH, BEGINNING WITH FIRST EGG 



In the preceding paragraphs we have used records that begin before 

 a definite date — viz, December i. On being examined from the stand- 

 point of the first egg it will be observed that the production for any one 

 month, say December, is made up of the production of birds that have 

 been laying for varying intervals of time, including those well along in 

 production and those just beginning. In Table XII the rate of pro- 

 duction has been examined from another standpoint. Three periods of 



